1. Technical Field of the Invention
The present invention relates to telecommunications networks and, in particular, to routing Signaling System 7 (SS7) over an Internet Protocol (IP) based communications network.
2. Description of Related Art
A typical telecommunications switch or exchange is a complex digital processor comprising a vast number of devices, signal terminals and, most importantly, software and hardware modules for providing telecommunications services to telecommunications users. With the development of the aforementioned digital processor and a Common Channel Signaling (CCS) network system, such as a Signaling System 7 (SS7) telecommunications network, a typical telecommunications network is now able to support and transport much more than mere voice data. Such data might include video images, control signals, or application specific information.
Also with the wide proliferation of Internet Protocol (IP) based communications networks, otherwise also known as the Internet, a number of telecommunications vendors and service providers are interworking or interfacing the existing CCS network system with the newly developed IP based communications networks. Such an interface would enable an end user, such as a telecommunications subscriber, to communicate multimedia data over a packet based communications network rather than over a conventional CCS network system. Such an interface provides a number of advantages such as higher bandwidth connections. As an illustration, a first Public Switched Telephone Network (PSTN) subscriber connected to a first local switch communicates with a second PSTN subscriber connected to a second local switch over an IP network using a higher bandwidth connection than conventionally available over an SS7 telecommunications network. Such an interconnection is further advantageous since it is more economical to provide an IP connection than to establish or maintain an SS7 telecommunications network.
Now referring to FIG. 1, a block diagram of a local switch connected to an Internet Protocol (IP) based communications network using an interworking function (IWF) is illustrated. A local switch 10A serving a plurality of subscriber terminals (not shown in FIG. 1) determines whether a destination node, such as a destination local switch 10B, is communicable over an IP network 110. In response to such a determination, the local switch communicates with an interworking function (IWF) 35A via an interface (IT) 37A to convert the SS7 signal to acceptable IP format and transmits the data over the IP network 110 to another IWF 35B connected to the destination local switch 10B. The actual mechanism and the specifications for converting or encapsulating the SS7 signal within an IP packet will not be disclosed in detail herein. A standardization organization called Internet Engineering Task Force (IETF) has formed working group Signal Transport (SIGTRAN) within its Transport Area to formulate and implement the necessary specifications for transporting SS7 signal over an IP transport network. All such standardization specifications as mandated by IETF SIGTRAN working group are fully incorporated by reference herein.
On the other hand, in response to a determination that the destination node is not connected to an IP network, the local switch 10A transmits necessary SS7 signals over to the connected SS7 network over its trunk interface 38A. In a conventional manner, the SS7 telecommunications network then communicates the call setup signal over to the destination local switch 10C for effectuating voice/data communication therebetween.
However, as described above, a digital local switch is a complex and sophisticated processor and it is not desirable to modify or alter an existing local switch to interface or interconnect to the new IP network. Furthermore, such a change at the switch level requires each and every local switch within a particular telecommunications network to be modified to interface to the IP IWF 35A. Lastly, it fails to utilize the reliability and robustness that is already provided within the existing SS7 telecommunications network. Accordingly, there is a need for a network solution wherein local switches transparently connect and interface with IP networks without requiring undesirable or complex changes therein.